Focused seismicity triggered by flank instability on Kīlauea’s Southwest Rift Zone.

Judson, J. and Thelen, W. A. and Greenfield, T. and White, R. S. (2017) Focused seismicity triggered by flank instability on Kīlauea’s Southwest Rift Zone. Journal of Volcanology and Geothermal Research, 353. pp. 95-101. ISSN 0377-0273 DOI

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Swarms of earthquakes at the head of the Southwest Rift Zone on Kīlauea Volcano, Hawaiʻi, reveal an interaction of normal and strike-slip faulting associated with movement of Kīlauea's south flank. A relocated subset of earthquakes between January 2012 and August 2014 are highly focused in space and time at depths that are coincident with the south caldera magma reservoir beneath the southern margin of Kīlauea Caldera. Newly calculated focal mechanisms are dominantly dextral shear with a north-south preferred fault orientation. Two earthquakes within this focused area of seismicity have normal faulting mechanisms, indicating two mechanisms of failure in very close proximity (10's of meters to 100 m). We suggest a model where opening along the Southwest Rift Zone caused by seaward motion of the south flank permits injection of magma and subsequent freezing of a plug, which then fails in a right-lateral strike-slip sense, consistent with the direction of movement of the south flank. The seismicity is concentrated in an area where a constriction occurs between a normal fault and the deeper magma transport system into the Southwest Rift Zone. Although in many ways the Southwest Rift Zone appears analogous to the more active East Rift Zone, the localization of the largest seismicity (>M2.5) within the swarms to a small volume necessitates a different model than has been proposed to explain the lineament outlined by earthquakes along the East Rift Zone.

Item Type: Article
Additional Information: Tilt data are available at ScienceBase with the following link:
Uncontrolled Keywords: 2017AREP; IA72
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
06 - Part-III Projects
08 - Green Open Access
12 - PhD
Journal or Publication Title: Journal of Volcanology and Geothermal Research
Volume: 353
Page Range: pp. 95-101
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 03 Jul 2017 23:24
Last Modified: 03 Dec 2018 12:06

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